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Amplitude
About: Amplitude is a research topic. Over the lifetime, 46213 publications have been published within this topic receiving 733850 citations.
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TL;DR: In this article, the authors examined the alternative of carrying out the migration through a reverse time extrapolation, which may offer improvements over existing migration methods, especially in cases of steeply dipping structures with strong velocity contrasts.
Abstract: Migration of stacked or zero-offset sections is based on deriving the wave amplitude in space from wave field observations at the surface. Conventionally this calculation has been carried out through a depth extrapolation. We examine the alternative of carrying out the migration through a reverse time extrapolation. This approach may offer improvements over existing migration methods, especially in cases of steeply dipping structures with strong velocity contrasts. This migration method is tested using appropriate synthetic data sets.
1,274 citations
TL;DR: In this paper, a continuous finite bandwidth of modes can be incorporated into the description of post-critical Rayleigh-Benard convection by the use of slowly varying (in space and time) amplitudes.
Abstract: The main purpose of this work is to show how a continuous finite bandwidth of modes can be readily incorporated into the description of post-critical Rayleigh-Benard convection by the use of slowly varying (in space and time) amplitudes. Previous attempts have used a multimodal discrete analysis. We show that in addition to obtaining results consistent with the discrete mode approach, there is a larger class of stable and realizable solutions. The main feature of these solutions is that the amplitude and wave-number of the motion is that of the most unstable mode almost everywhere, but, depending on external and initial conditions, the roll couplets in different parts of space may be 180° out of phase. The resulting discontinuities are smoothed by hyperbolic tangent functions. In addition, it is clear that the mechanism for propagating spatial nonuniformities is diffusive in character.
1,185 citations
TL;DR: In this paper, an experimental setup has been constructed for simultaneous measurements of the frequency, the absolute Q factor, and the amplitude of oscillation of a quartz crystal microbalance (QCM).
Abstract: An experimental setup has been constructed for simultaneous measurements of the frequency, the absolute Q factor, and the amplitude of oscillation of a quartz crystal microbalance (QCM). The technical solution allows operation in vacuum, air, or liquid. The crystal is driven at its resonant frequency by an oscillator that can be intermittently disconnected causing the crystal oscillation amplitude to decay exponentially. From the recorded decay curve the absolute Q factor (calculated from the decay time constant), the frequency of the freely oscillating crystal, and the amplitude of oscillation are obtained. All measurements are fully automated. One electrode of the QCM in our setup was connected to true ground which makes possible simultaneous electrochemistry. The performance is illustrated by experiments in fluids of varying viscosity (gas and liquid) and by proteinadsorptionin situ. We found, in addition to the above results, that the amplitude of oscillation is not always directly proportional to the Q factor, as the commonly used theory states. This puts limitations on the customary use of the amplitude of oscillation as a measure of the Q factor.
1,172 citations
TL;DR: In this paper, the authors examined the circumstances under which finite disturbance amplitude solutions of the coupled wave equation can be obtained in the vicinity of the resonant field line, and the relevance of recent experimental work to the problem was pointed out.
1,134 citations